1. Field of the Invention
This invention relates to interfitting plastic panels, and more particularly to plastic panels or planks comprising a plurality of plastic panels interlocked in side by side relation.
2. Description of the Prior Art
Heretofore, plastic panels or planks have been provided for various structures, such as covers for swimming pools. For example, a plurality of generally similar planks have been formed heretofore of an extruded plastic material, such as polyethylene or polyvinylchloride (PVC) into hollow shapes having edges which are interlocked or connected to each other to form the desired structure.
As an example, reference is made to U.S. Pat. No. 4,577,352 dated Mar. 25, 1986 which shows a cover for a swimming pool having a plurality of hollow extruded plastic sections or planks with each section including a plurality of hollow compartments. Adjacent longitudinally extending sections have interfitting male and female edge portions for connecting adjacent sections together. The interfitting male and female portions, such as tongue and groove connectors, are arcuate and tend to pivot relative to each other about the arcuate joint thereby permitting articulation between adjacent plank sections which may provide an uneven surface appearance to the cover. Adjacent sections are staggered lengthwise for connection of adjacent sections. End plugs are provided to close the ends of the hollow compartments. Because adjacent sections are staggered in order to provide interlocking, at least two different lengths of planks or sections are required.
U.S. Pat. No. 4,749,606 dated Jun. 7, 1988 shows a plurality of floating pads of a hexagonal shape forming a gapless insulating cover for floating on a liquid such as a slurry. The insulating cover prevents heat loss by convection from the surface of the liquid. Each floating pad is formed of a low density polyethylene and has a hexagonal hollow shape.